This invention pertains to coatings that protect glass-like surfaces from paint or other coating materials while at the same time acting as a primer or undercoating for non-glass surfaces. The coatings show high adhesion to non-glass surfaces and low adhesion to glass-like surfaces so that they may be removed from the glass-like surfaces while remaining tightly bound to the non-glass surfaces.
It is often desirable to provide a finished (e.g. painted, varnished, shellacked, or otherwise overcoated) surface in proximity to a non-finished surface on a wide variety of articles. Thus, for example, it is frequently desired to paint a window frame and/or the juncture between the window frame and the glass, without painting the glass itself. A similar problem arises in other contexts, including but not limited to painting adjacent to trim or glass on automobiles, painting mirror frames, and so forth.
Such painting or other overcoating is often accomplished by the careful manual application of the overcoat. This method can be difficult, time consuming and require an inordinate painting skill. Other methods include painting at will on the glass surface or window pane while painting the non-glass surface. A scraper or razor blade is then used to remove the paint from the glass-like surface. While ordinary paint can be scraped off within hours after being applied, after that short period it may adhere to the glass surface strongly. In addition, particularly where the underlying "glass" surface is a soft material (e.g., an acrylic plastic) the scraping procedure may often mar the surface.
Yet another method involves masking. With masking, a covering (e.g., newspaper and/or tape) is placed on surface it is desired to protect from the overcoating (e.g., painting) operation. The non-glass surface is painted and the masking material is removed leaving the glass-like surface essentially free of paint or other overcoating. This method, however, requires the time-consuming operation of carefully applying the masking materials so that they line up with and abut the juncture at the edge of the glass-like material.
Finally, another masking approach involves the use of a "paint on" acrylic coating that dries to form a continuous film. The coating adheres weakly to a glass-like surface, but tightly to a non-glass surface. After application of a finish to the masked object, the acrylic coating is removed from the glass-like (masked) area, but not from the non-glass area. This leaves the glass-like area that area essentially free of the finish material (see, e.g. PCT application WO 92/02307).